A microscale model for combined CO(2) diffusion and photosynthesis in leaves

Area of Science:

• Plant Physiology
• Biophysics
• Photosynthesis Research

Background:

• Understanding carbon dioxide (CO2) transport within plant leaves is crucial for optimizing photosynthesis.
• Previous models often simplified leaf internal structure, potentially limiting accuracy in gas exchange simulations.

Purpose of the Study:

• To develop and validate a 2-D microscale model of CO2 transport coupled with photosynthesis in wheat leaves.
• To investigate the influence of leaf microstructure on gas exchange and photosynthetic efficiency.

Main Methods:

• A biophysical microscale model incorporating 2-D leaf tissue geometry and diffusive CO2 mass exchange was developed.
• The model was integrated with the Farquhar-von Caemmerer-Berry biochemical model of photosynthesis.
• Model predictions were validated against experimental gas exchange and chlorophyll fluorescence measurements in wheat.

Main Results:

• The combined model generally showed good agreement with experimental data.
• A discrepancy was noted in mesophyll conductance predictions under high CO2 and low light conditions, suggesting unmodeled physiological processes.
• The model successfully elucidated the impact of ambient CO2 concentration and light intensity on stomatal and mesophyll conductance.

Conclusions:

• The developed model provides a detailed understanding of CO2 diffusion coupled to photosynthesis at the leaf tissue level.
• Accounting for actual leaf microstructure is vital for accurate simulation of gas exchange.
• Further refinement is needed to incorporate additional physiological factors influencing photosynthesis under specific conditions.